Most pushbutton operators are installed in some type of enclosure such as an electrical box, panel board or machine station. The pushbutton is generally a multi component device, which include a button assembly located outside of the enclosure, a mounting block located inside of the enclosure and one or more electrical contact blocks attached to the mounting block and operated by the button assembly. In most applications a wall of the enclosure is clamped between the button assembly and the mounting block. Once the button assembly and mounting block are installed on the wall the pushbutton generally remains firmly attached to the wall. However, the function of some pushbuttons, such as shutting down equipment during an emergence, can result in situations where a human operator under stress hits the button with sufficient force to cause the contact block to become dislodged or sufficiently loose from the mounting block or the mounting block to become disconnected or separated from the button assembly. Sufficiently loose, as used herein, is defined to mean a condition in which proper operation of the pushbutton does not cause the electrical contacts of an attached contact block to change states. Interlocks for detecting a separation between the mounting block and the contact block are known. However, either situation can result in a condition where the pushbutton is prevented from properly operating the contact block. The thickness of the wall on which the pushbutton switch assembly is installed can also affect the operation of an interlock in detecting sufficient looseness of the mounting block or contact block. Therefore, it is desirable to have a mechanical interlock that will automatically open an electrical interlock contact if any part of the assembly become sufficiently loose that the pushbutton is not able to properly operate the electrical contact blocks connected to it.